SAN
DIEGO—Biotechnology company BioAtla LLC has announced the establishment of a license and option agreement with Pfizer Inc. to advance the development
and commercialization of a new class of antibody therapeutics based on the combination of BioAtla's Conditionally Active Biologic (CAB) platform and
Pfizer's proprietary antibody drug conjugate (ADC) payloads.

BioAtla's CAB proteins can be developed in a
variety of formats, including naked monoclonal antibodies, ADCs, immune checkpoint inhibitors, bispecific antibodies and chimeric antigen receptor T cells.
Tumor microenvironments generally present with highly specific conditions, and CAB-designed mAbs can be developed to deliver a therapeutic payload and/or
recruit the immune response in specific and selected locations and conditions in the body. A CAB antibody's selective activation is the result of amino
acid substitutions of human-like sequences made to ensure compatibility, which results in both a reduced risk of immunogenicity and an improved manufacturing
yield of the drug.

CAB-ADC antibodies offer a new way to confront the limitations of existing ADC antibody
technology. This approach actively binds to antigens expressed on tumor tissue-resident cancer cells, but not to the some antigens expressed by normal cells
in non-diseased tissues, allowing for more specific targeting of tumor tissues, increasing efficacy while minimizing off-target effects.

“This agreement between Pfizer and BioAtla provides an exciting opportunity to further explore innovative and
potentially breakthrough technologies in the treatment of human cancers,” commented Bob Abraham, senior vice president and head of Pfizer’s
Oncology-Rinat Research & Development Group. “By leveraging the unique capabilities of the two companies, we hope to advance our mission to deliver
safer and more effective medicines to our patients.”

Per the terms of the agreement, Pfizer and BioAtla will
each gain a license to the other's respective technology to pursue the development and commercialization of several CAB-ADC antibodies. Pfizer will also
receive an exclusive option to develop and commercialize BioAtla CAB antibodies that target CTLA4. Should the work prove successful, BioAtla's platform
could allow the selective targeting of CTLA4 expressed on immune cells localized in the tumor microenvironment. Both companies stand to receive milestone
payments and royalties based on individual CAB-ADC antibody candidates developed and commercialized by the other party. All told, including the CTLA4 option
and license, BioAtla could receive more than $1 billion in upfront, regulatory and sales milestone payments, in addition to tiered marginal royalties
reaching double digits on potential future product sales.

“CAB-ADC antibodies and CAB immune checkpoint
inhibitors such as those targeting CTLA-4 can potentially improve current therapies and enable combination immuno-oncology treatments for many cancers. This
agreement combines the therapeutic effectiveness of Pfizer’s clinically validated ADC technology with the safety and expansive receptor applicability
of BioAtla CAB antibodies,” Dr. Jay M. Short, co-founder, president, CEO and chairman of the board of BioAtla, remarked in a press release. “We
are enthusiastic about working with Pfizer to develop these novel products with strategic importance in building BioAtla’s portfolio of proprietary
products.”